Officials say 2018 has been the deadliest start to the Maryland boating season in six years.

State Natural Resources Police and the U.S. Coast Guard told news outlets Friday that four boaters have died since April 4. Police superintendent Col. Ken Ziegler and Coast Guard Lt. Cmdr. Sara Wallace say none of the four was wearing a life jacket and one would have provided enough time until help could arrive.

Boaters should wear the jackets because trying to put one on in an emergency is too risky, especially with cold hands. The temperature under the Chesapeake Bay Bridge was 49 F (9 C) shortly before noon Friday, and 60 percent of people who fall into water below 50 F drowned.

Boaters found without jackets or other safety equipment will be sent back to land.